CDC is collaborating with public health and regulatory officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Listeria monocytogenes infections (listeriosis). The joint investigation indicates that Les Frères, Petit Frère, and Petit Frère with Truffles cheeses made by Crave Brothers Farmstead Cheese Company of Waterloo, Wisconsin is the likely source of this outbreak.

Public health investigators are using DNA “fingerprints” of Listeria obtained through testing with pulsed-field gel electrophoresis, or PFGE, to identify cases of illness that may be part of this outbreak. They are using data from PulseNet, the national subtyping network of state and local public health laboratories and federal food regulatory laboratories that performs molecular surveillance of foodborne infections.

A total of five persons infected with the outbreak strain of Listeria monocytogenes have been reported from four states. The number of ill people identified in each state is as follows: Illinois (1), Indiana (1), Minnesota (2), and Ohio (1).

Among persons for whom information is available, dates that illness was diagnosed range from May 20, 2013 to June 17, 2013. All five ill persons were hospitalized. Ill persons range in age from 31 years to 67 years, with a median age of 58 years, and 80% are female. One illness in a pregnant woman resulted in a miscarriage. One death was reported in Minnesota.

The outbreak can be visually described with a chart showing the number of persons who were diagnosed each day. This chart is called an epidemic curve or epi curve. Clinical specimens that were collected after June 22, 2013 might not be reported yet due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 3 weeks.

About 800 laboratory-confirmed cases of listeriosis are reported each year in the United States, and typically 3 or 4 outbreaks are identified and reported to CDC annually. Some foods that have been linked to outbreaks in recent years are Mexican-style soft cheeses, imported ricotta salata cheese, whole cantaloupe, raw sprouts, and precut celery.

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback investigations conducted by officials in local, state, and federal public health, agriculture, and regulatory agencies indicate that Les Frères, Petit Frère, and Petit Frère with Truffles cheeses manufactured by Crave Brothers Farmstead Cheese Company is the likely source of this outbreak of listeriosis.

In interviews, ill persons answered questions about foods consumed and other exposures in the month before becoming ill. All five ill persons reported consuming a soft cheese. Information about specific cheeses consumed is available for four of the ill persons. Of those, three either definitely or probably ate Les Frères cheese made by Crave Brothers before getting sick. Investigation of specific types of cheeses consumed by other ill persons is ongoing.

Laboratory tests conducted by the Minnesota Department of Agriculture on samples of Les Frères and Petit Frère with Truffles cheeses made by Crave Brothers from two retail stores indicate the presence of the outbreak strain of Listeria monocytogenes. Further testing and confirmation of the results are pending.

On July 3, 2013, Crave Brothers Farmstead Cheese Company of Waterloo, Wisconsin voluntarily recalled its Les Frères, Petit Frère, and Petit Frère with Truffles cheeses with make dates of July 1, 2013 or earlier due to possible Listeria monocytogenes contamination. The recalled cheeses were distributed nationwide through retail and foodservice outlets as well as by mail orders.

The FDA is conducting an inspection at Crave Brothers' processing facility in coordination with the Wisconsin Department of Agriculture. FDA is working closely with CDC, Crave Brothers, and public health authorities in states where illnesses occurred to determine the exact cause of contamination.